Five Test defeats in a row -- just nine months after being crowned the world's top-ranked team -- have left the sport-obsessed country convulsed over the downward spiral of the national team.

Cricket Australia's under-fire chief James Sutherland admitted they were "lucky to be a top 10 side" after the abject surrender to South Africa by an innings in the second Test in Hobart.

Captain Steve Smith confessed he was "embarrassed" and "humiliated" but now faces the prospect of crashing to an unprecedented 3-0 series defeat in this week's final day-night Test in Adelaide.

Why Australia have fallen so far so quickly is complex. But former greats say the demise has been long coming.

They point to the diminution of the bedrock domestic Sheffield Shield four-day competition, increasing commercial pressures from the popular Big Bash Twenty20 League and idiosyncratic match scheduling.

The 124-year-old Shield has been devalued by using it as training run for Test players, introducing experimental rule changes such as substituting bowlers, and stunting the career path of young promising players.

Former Test captain Ricky Ponting, a leading candidate to succeed Rod Marsh who quit last week as chairman of selectors, believes cricket is suffering a brain drain.

Too many coaches

Rather than coaching at state level or helping the national team, Ponting currently commentates on TV and radio as do former Test luminaries such as Mark Taylor, Shane Warne, Ian Healy, Michael Clarke and Michael Slater.

"Cricket Australia know this. If you look through the greats of the game, how many of those guys are actually back inside the system coaching somewhere?" said Ponting.

"They’re not. They’re all sitting back behind a microphone commentating because they get paid more and it's less intrusive time-wise.

"I think it's something that needs to be looked at."

Wicketkeeping great Healy has called for a more streamlined structure believing that the Australia national team's cricket coaching is "totally over-serviced".